Drill grinding jig



Nov. 24, 1953 Filed Jan. 22, .1951

H. c. READING 2,660,008

DRILL GRINDING JIG 4 Sheets-Sheet 1 INVQNTO'R B w GAM/ MM M Nov. 24, 1953 H. c. READING 2,660,008

DRILL GRINDING JIG Filed Jan. 22, 1951 4 SheetsSheet 2 ,mn-m- 1 NOV. 24, 1953 H, c, READING 2,660,008

DRILL GRINDING JIG Filed Jan. 22, 1951 4 Sheets-Sheet s mm m 1, a Y r "m ll 10 N ro H. C. READING DRILL GRINDING JIG Ngv. 24, 1953 4 Sheets-Sheet 4 Filed Jan. 22, 1951 INveMToR I N-Q. M7 zz wazzo ke MIFMI Patented Nov, 24, 1953 UNITED STATES E ATENT OFFICE 13 Claims.

This invention relates to drill grinding jigs of the kind in which a guide is provided for 10- eating the drill longitudinally, a mounting for towards or away from the grinding face so as to vary the radius'of curvature of said facet according to the size of the drill, and means for adjusting'the distance apart of the swing axis and the drill axis in a direction normal to and inter- "secting both of them so that a varying degree of clearance or backing away of the facet from its cutting edge maybe obtained according to the size of the drill, which distance apart is generally referred to as the f dimension.

According to this invention, a drill grinding "jig of' the kind referred to is characterised in that means are provided for adjusting the drill guide together with the swing axis in a direction towards and away from the grinding face and 0 means for adjusting the drill guide independently of the axis of swing in a direction which has both a component in a direction along the axes of the drill and a component in the direction of V a line which is normal to and intersects'both the swing axis and the drill axis. 7

There are provided means for determining the extent of both said adjustments required for different sized drills, which means are dependent .on data compiled as a result of experience in connection with the best radius of curvature for the facets of different sized drills and the best f dimension.

The, aforesaid determining means may be visual, for example by the provision of suitable calibrated scales, or may be by way of different sized gauge pieces which. are introduced between relatively movable abutments provided for each adjustment.

'For example," the abutments may be so arranged that the drill to be ground may be employed as the gauge by introducing its shank between the abutments and bringing the abutments together.

It will be appreciated that the first of said adjustments referred to above will result in 'a change of the gap between the end of the drill guide and the grinding face. A feature of the invention consists in that the direction of move- .ment of the second adjustment is so "selected that after the two adjustments have been'efiecv ed appropriate to any size of drill, the gap remains substantially the same or within such limits, that the overhang of the drill is not detr imental to effective grinding.

As is known, at one limit of the swinging movement of the drill guide, the drill should be so located that its cutting edge is always in a definite angular disposition, i. e. as viewed along the axis of the drill, it should be at right angles to a line normal to and intersecting the swing axis and the drill axis. Various means for locating the drill in this position have been proposed for association with the drill guide.

The drill guide comprises a trough having sides disposed in the manner of a V and said locating means comprises a platform upstanding from the forward end of that side of the guide remote from the face of the drill to be ground, the inwardly directed face of which platform is so shaped and disposed as to engage a corner of the drill at the junction between its cutting edge (not being ground), the edge of a flute, and the circumferential edge of a facet (not being ground), and which platform irrespective of the size of the drill being ground locates the cutting edge always in the same angular position with respect to the sides of the trough and to the aforesaid axes.

The face of said platform may be flat and may be inclined at an angle of about 10 /2" to that face of the guide from which it plane is at an angle of about 10 to a plane bi-n secting the angle between the sides of the V.

The aforesaid drill guide may pe formed in two parts relatively movable along the longitudinal axis of the drills so as to accommodate different lengths of drills. The movable part of the guide may be mounted on a slide and also movably mounted on the slide is an adjustable abutment for engagement with the end of the drill, whereby after initial setting up of the guide and swing axis, the drill may be fed forward against the grinding face by a predetermined amount, and thus each facet may be ground to a similar extent. For this purpose; a micrometer gauge is associated with the adjustable abutment. V

In moving the drill along the guide, the'aforesaid corner remains in contact with the platform until the facet to be ground engages the grinding wheel, whereupon the drill is preferably clamped in this position and the guide is then swung about the aforesaid swing axis. An appropriate handle fixed to the guide may be provided for this purpose. A feature of the invention consists in the clamping means for the drill being provided with a manipulating member so arranged that irrespective of the size of the drill being clamped it remains in a convenient position for manipulation while the operators hand is gripping the handle for swinging the drill guide. For this purpose there may be pivoted above one side of the V guide, two lever-arms arranged one above the other, the lower one of the two leverarms being provided with a nose-piece which sengages the drill and the other of which lever-arms is provided with a nose-piece which engages a cam face at the end of the first said lever, which cam face is so shaped that irrespective of the position of the first said lever for varying sizes .of

the drill, the second lever will be located by its nose-piece such that the outer end remains approximately in the same position with respect to the handle secured to the V guide and so that by pressing on the end of the second lever, the drill is pressed into the -V guide.

The following is a more detailed description of i a-drill ,jig for use in a grinding machine in which a peripheral face of the grinding wheel is emthe drill guide,

ployed, reference being made to the accompanying drawings in which- Figure 1 is a plan view of the drill jig without Figure 2;is an elevation looking in the direction of the arrow in Figure 1,

Figure 3 is a part-sectional view on the line 33 of Figure 1,

Figure 4 is a part-sectional view on the line-44 of Figure 1,

Figure :5 is a plan view of the drill guide and clamp, and

Figure 6 is an end elevation of the drill guide looking from the left of Figure 5.

A base plate H3 is arranged for attachment to a platform on the grinding machine and .is pro- 7 vided with an upstanding spindle H so located that its axis i2 .is tangential to the grinding wheel -I 3 and is centrally disposed across the width thereof. Mounted on this upstanding spindle is a plate M which is substantially sector-shaped in contour and extends laterally to one SldByOf the grinding wheel. The arcuate edge of the plate 7 is provided with graduations 1-6 which cooperate with an index I! on the base plate. Clamping position on the slideway, which clamping means comprises a threaded spindle 23 which engages a nut portion 59 in the fixed slide i9, which spindle is provided with a head '59 which engages a face of the pillar 22, the spindle sliding through a slot 6i formed in the slideway 9. The pillar 22 is substantially rectangular in horizontal cross-section (see Figure 1) with the sides inclined to the length of the slideway. Two opposite faces at the top of the pillar are provided with conical depressions 24 and arranged over the top of the pillar is an inverted trough-shaped member 25, the end walls 26 of which are provided with conical ended pins 27 which engage the aforesaid depressions 2 1, one of which is in screw-threaded engagement with the end wall and is adjustable by the knob 3|. The inverted trough has secured to it an arm 28 extending in the direction of the length of the slideway, the end of which arm is provided with a laterally-extending manipulating handle 29 whereby the arm and the inverted trough member may be rocked about the pivot axis 30 provided by the conical pins 21 and recesses 24. The aforesaid arm is provided on a side face thereof with a slide way 32 in which is mounted a slide 33 having secured thereto a drill guide 34 Figure 5. The slideway 32 is so disposed on the arm 28 that when the arm has been rocked into a position in which the locus of the adjusting movement of a point on the slide lies in a plane parallel to a plane containing the aforesaid axis {2 thenthat locus as viewed at right angles to these planes subtends an angle of about 38 to the pivot axis 30.

The sides of 35, 36 (see Figure 6), of the drill guide include an angle of .90 between them and the drill guide is so disposed :on the slide 3.3 that when the arm 28 is moved into aposition in which the line along the bottom of the if lies in a plane containing the axis l2 then a plane intersecting the angle between said sides is at an angle of about 10 to the plane containing the axis I2 and the lineat the bottom of the V, Qlampingmeans 571' are provided for fixing the slide in the slideway. Pivoted one above the other to the drill guide above the side 36 are the two clamping levers 3?, 39 hereinafter referred to. The lower lever 3'! is arranged to clamp the drill .39 in the V guide. The end of the-upper lever-arm .38is arranged to extend laterally to one side of the .drill guide .and is provided with a thumb piece 49 :in the region -.of the aforesaid manipulating handle 29. The lever 38 is provided with .a nose-piece 4| which engages a cam .faceM on the lower lever 31 so as to engage the end 43 of the lower :lever 31 with the drill irrespective of the size-of the drill. Referring to Figure v2 it will be seen that the slide way 19 and slide 2| are provided with abutment faces .44 .and 45 respectively; Similarly the slide 33 and slideway 32 are provided with abutment faces 46 and 41. These pairs of abutment faces arearr-anged to accommodate the shank of a drill and are so inclined to the direction of movement of the slides that when -a drill is placed between either pair of abutments; it will locate the slide in the appropriate position for grinding thatpar= ticular drill.

The end of the drill guide 3 5 adjacent the grinding wheel I3 (see Figure 5) has the side 36 thereof which is adjacent the race being ground cut away at 4B in a vertical plane at an angle to the longitudinal axis of the guide 34 while the other side of the guide is provided with a platform 49 for locating the corner of the .drill in the manner referred to above.

As will be seen from Figures 5 and 6 the drill guide 34 is provided with a rectangular slot in which is secured a slotted bar by set screws 5|. .Slideably mounted on the slotted bar is a second drill guide 52 of similar shape to the drill guide 34. The second guide is held in position by a set screw 53 which passes through the slot 54 (Figure 6) of the bar and engages .a threaded hole inthe guide 52. Preferably a washer 56 is disposed between the head of each set screw and bar.

Similarly mounted on the slotted bar is an adjustable abutment 55 in the form of a VGII'IlGl head by which the drill may be fed along the guide into engagement with the grinding wheel.

It will be appreciated with the above arrangement that when the slide 2[ is moved to the left in Figure 1 the drill guide together with the axis of pivoting 30 will also be movedrto the left and the end of the drill will be withdrawn from the grinding wheel I3. If the s1ide33 is then moved to the right in the slideway 32 so as to bring the end of the drill again into contact with the grinding wheel, since the axis of to the variation of the radius of curvature for different sized drills is that the radius of curvature of that part of the facet where the cutting edge joins the flank of the drill shall be equal to or slightly less than the diameter of the drill. It will be appreciated that since the V-shaped guide is not symmetrically disposed (as will be seen from Figure 6) then with the increase of size of the drill the axis of the drill will be thrown to the right, thus the extent of movement of the slides 2| and 33 towards and away from the grinding wheel is not directly proportional to the diameters of the drills. It does however follow a straight line law and thus by inclining the faces of the abutments M and 45 andalso by inclining the slide 32 it is possible to set the apparatus for the required radius of curvature by gripping the shank of a drill between the faces of the abutments. Reference has already been made to the f dimension which determines the extent of cutting clearance and is dependent on the distance apart of the swing axis where they cross one another and the drill axis. The dimension is required to vary with different sized drills. It will also be appreciated that when different sized drills are placed in the drill guide, the distance between the axis of the drill and the swing axis will be varied but not to the required extent for the J dimension. Thus it is necessary to impart to the drill tation of the grinding wheel, a slide adjustable in the slideway, a pillar fixed to the slide, an arm pivotally engaging the pillar so as to swing about a second axis which is inclined to the plane containing the first axis at an angle determined by the rotating adjustment of the first slideway, a second slideway on said arm, a second slide in second slideway, and a drill guide fixed to the second slide and extending in a direction towards the periphery of the grinding wheel which second slideway extends in a direction having a component in a direction towards and away from the periphery of the grinding wheel and a component in a direction parallel to the first said axis.

2. The combination according to claim 1 wherein a scale and index device are associated with the base and first slideway.

3. The combination according to claim 1 wherein the second slideway extends in a direction towards the base at an angle of about 38 to a line normal to the first said axis.

4. The combination according to claim 1 wherein a gauge is associated with the first said slideway and with the second slide and slideway for presetting the extent of movement thereof in accordance with the size of drill to be ground.

5. The combination according to claim 4 wherein each gauge comp-rises abutments on the slide and slideway extendingtransversely to the movement of the slide and having opposed faces between which the shank of a drill may be disposed.

6. The combination according to claim 1 wherein the drill guide comprises a trough having its sides disposed in the manner of a V and locating means comprising a platform upstanding from the forward end of that side of the V guide remote from the face of the drill to be ground and upwardly directed face of which platform is adapted so as to engage a corner of the drill at the junction between its cutting edge (not being ground), and the circumferential edge of a facet (not being ground) whereby the platform irrespective of the size of the drill being ground locates the cutting edge always in the same angular position with respect to the sides of the guide, a movement having a vertical component.

This is effected by inclining the slideway 32 so that as the drill guide is moved towards the grinding wheel the drill guide is lowered. Again in this instance by suitably selecting the angle of inclination of the abutment faces 46 and 4'! the required adjustment for f dimension may be automatically reobtained by placing a drill between these faces and bringing them together.

'In the case where the swing axis is inclined to the peripheral face of the grinding wheel as shown in Figure 1 of the drawings the angle of inclination. of the slide 32 to the swing axis should be about 38 under the conditions defined earlier in the specification in order to obtain the required conventional f dimension, while the angle of inclination of the abutment faces 45 and 41 to the horizontal should be about 56".

I claim: I

l. The combination with a rotatably mounted grinding wheel of a drill grinding jig comprising. a base, a first slideway rotatably adjustable on the base about a first axis tan ential to a circle concentric with the grinding wheel, which slideway extends obliquelyv to the axis of rotrough and the aforesaid axes.

7. The combination according to claim 6 wherein the face of said platform is flat and is inclined at anangle of about 10 to that face of the guide from which it projects.

8. The combination according to claim 6 wherein the drill guide is so mounted'in the second slide that when that slide has been moved about the second axis so that the plane containing said first axis also contains the line along the bottom of the V groove that plane is then at an angle of about 10 to a plane bisecting the angle between the sides of the V.

9. The combination according to claim 1 wherein said drill guide is formed, in two relatively movable parts disposed apart along a longitudinal axis of the drill so as to accommodate different lengths of drills.

10. The combination according to claim 9, wherein the movable part of the drill guide is mounted on a third slide on which slide is also movably mounted an adjustable abutment for engaging the end of the drill for the purpose described. I

11. The combination according to claim 10, wherein said ajustable abutment comprises ,a micrometer gauge. 7 v s '12. The combination according to claim 1 wherein the second slideway is provided with a hand grip for effecting the swinging movement and wherein clamping means are provided for securing the drill in the drill guide, which clamping means are disposed adjacent the hand grip.

13. The combination according to claim 12 and having a V-shaped drill guide wherein there are pivoted above one side of this V guide two lever arms arranged one above the other the lower one of the two lever arms being provided with a. nose-piece which engages the drill and the other of which lever arms is provided with a nosepiece which engages a cam face at the end of the first said lever which cam face is so shaped that irrespective of the position of the first said lever for varying the sizes of the drill the second lever will be located by its nose-piece such that its free end remains approximately in the same position with respect to the handle grip secured to a part carrying the V-guide and so that by pressing on the end of the second lever the drill is pressed into the v guide.

HAROLD CORNELIUS READING.

References Cited in the file of this patent UNITED STATES PATENTS 

